1. Field of the Invention
The present invention relates to a servo control system, and specifically relates to a servo control system that has the function of automatically adjusting a learning controller.
2. Description of Related Art
In recent years, techniques related to learning control have been in practical use in machine tools. The learning control is, in brief, a control that optimizes a feedforward signal with respect to certain same operations. By performing the same operations in a repeated manner, the feedforward signal is updated and finally converges to a specific form. Learning is ended at that point in time, and the feedforward signal obtained by the learning control is used as is without being updated.
The principle of a high accuracy control of repeated operations using a learning control is reported (for example, Tadashi INOUE et al.: High Accuracy Control of Play-Back Servo Systems, the Institute of Electrical Engineers of Japan. C, Vol. 101, No. 4, pp. 89-96, (1981), hereinafter called “non-patent document 1”). In the non-patent document 1, an evaluation function itself is derived. However, the non-patent document 1 does not describe the technique of measuring a frequency response of servo systems and an experimental modal analysis, and hence calculates only nominal characteristics. The non-patent document 1 refers to the principle of a configuration method of a learning controller, but does not refer to the principle of a concrete adjustment.
The characteristics and stability of a learning control are also reported (for example, Tsuyoshi KATAYAMA et al.: Adaptive Learning Control Method for Optical Disk Drive Tracking Control, the Journal of the Institute of Television Engineers of Japan, Vol. 48, No. 8, pp. 1018-1026, (1994), hereinafter called “non-patent document 2”.) However, the non-patent document 2 does not refer to the principle of adjusting a learning controller.